1. Field of the Invention
The present invention relates to a spring lock or quick-connect tubular coupling for a pair of tubes one of which has an end portion telescopically disposed within an end portion of the other.
2. Discussion of the Related Art
In many automotive, household appliance and machine tool applications, fluid conduits or tubes that carry pressurized fluids must be capable of being disconnected to permit repair or replacement of components of the system.
U.S. Pat. No. 4,055,359 to McWethy discloses a quick-connect tubular coupling which facilitates initial connection and subsequent disconnection of the pair of tubes. McWethy was a key contribution to the art enabling manual connections of fluid pressure lines (100-300 psi) in a few seconds by using (i) a radially outwardly flared lip to expand and pass a garter spring thereby and (ii) a cage to retain the spring in the passed condition.
Specifically, McWethy utilizes an annular cage externally mounted on the inner tube in axially spaced relation to the free end of its end portion. The cage is held on the inner tube against axial displacement. The end portion of the outer tube is flared outwardly at its free end and is adapted to extend into the cage. A circular spring means is interposed between the flared end portion of the other tube and the cage and is disposed to prevent axial movement of one tube relative to the other. Between the telescoped end portions are a plurality of o-rings that are compressed in a sealed mode to prevent leakage through the coupling.
Assembly of the McWethy patent '359 is difficult in that the spring must be forced radially outwardly by the outwardly flared end portion until the spring expands to an extent greater than the diameter of the flared end. After this point is reached, the outer tube can continue its movement and the spring can then contact to a point such that it becomes interposed between the opposite side of the flare and the cage flange. This assembly requires substantial force to be exerted on the two tube ends to overcome the force required to expand the spring over the flared end. In locations where the open area is small, such as in some regions of an engine compartment, it can be difficult to make the connection because of the mechanical forces required to expand the spring.
Further the o-rings can be dry and this can also make a proper connection more difficult to obtain due to the additional frictional forces which have to be overcome as the two tube Portions are forced together.
Another problem with the McWethy patent '359 is that the spring may be able to come out of the cage when the two members are not connected. This happens in the McWethy design because part of the spring can bend past the cage flange and allow the entire spring to fall out. This causes increased manufacturing time for replacing the missing spring or even can cause a faulty connection for springs which are missing and not replaced when the "connection" is attempted.
Thus with McWethy's device two significant problems remained: (1) assurance that the manual connection has been made and remains properly made, and (2) reducing the loads to be overcome manually, which is critical when working in limited access spaces. The art, in attempting to improve upon McWethy, was concerned only with the first aspect. Blair (U.S. Pat. No. 4,401,326) provided visible indicator of proper connections. Proctor (U.S. Pat. No. 4,632,434) made the connecting assembly from more simplified stock components; and Corzine (U.S. Pat. Nos. 4,728,130 and 4,750,762) provided split collets to relieve the deformable sealing means after connection. But the art continued to use the same general construction of McWethy which inherently demanded a relatively high level of manual exertion to achieve the quick connection.